Hi, We are using LED driver (LED2472GBTR) in one of our products. Can we make RGB[1:8] outputs high (VDD=3.3V)? If so how? Regards, Veera

VAkul.1 · ‎2021-08-23

Peter BENSCH · ‎2021-08-24

Welcome, @VAkul.1, to the community!

Actually, you only need to switch / OE inactive to have all outputs also inactive. However, the outputs are not push-pull stages, but current sinks, the current of which can be set with a resistor connected to iset.

Are you aware that VDD is not limited to 3.3V, but can be between 3...5V?

What do you want to achieve by setting all outputs high?

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

VAkul.1 · ‎2021-08-24

Hi Peter,

Thank you for the Reply.

Actually we don't want to inactive all outputs. We want to control R[1:8], G[1:8] and B[1:8] outputs independently.

Can we control these Outputs independently low or high (particular segment LED on/off). If so how?

Regards,

Veera

Peter BENSCH · ‎2021-08-24

Hi, Veera,

Of course, you can set all outputs independently of each other as you like. However, the LED2472G is controlled serially (works as a serial-parallel converter) and therefore the data of all 24 outputs have to be rewritten for every change of only one output, even if their level is unchanged.

Regards

/Peter

BTW: please don't use your email to answer, as it contains your phone number, which is visible worldwide for every reader of the community.

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

VAkul.1 · ‎2021-08-25

Hi Peter,

Thank you for the quick reply.

Can we make them (RGB[1:8]) independently Low (how many volts?) and High(how many volts?) for supply VDD=3.3V

In other words what is the logic levels of these outputs? How to control these Logic levels independently?

Regards,

Veera

Peter BENSCH · ‎2021-08-25

Hi, Veera,

as I already wrote: the outputs are not push-pull stages, but current sinks.

So you don't set an output voltage or a logic level there, but a current that should flow through the respective LED.

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

VAkul.1 · ‎2021-08-25

Hi Peter,

Thank you for your quick response...

Lets take a simple example. Lets take an LED and Anode of LED is connected to 3.3v supply and cathode of LED connected to one of the outputs of LED driver RGB[1:8], lets say R1. To make the LED ON and OFF, R1 should be in two states (logic levels) right. What are those two states? How to control those two states?

Regards,

Veera

Peter BENSCH · ‎2021-08-25

Did you understand how a current source works?

Beside the theory also available on e.g. Wikipedia (current sources work almost identical to current sinks), STMicroelectronics provides some basics about LED array driving, e.g. in AN3981.

To come back to your example: no, R1 is not a logic output with logic levels, instead a constant current is driven when the output is active and none when inactive.

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

VAkul.1 · ‎2021-08-29

Hi Peter,

Thank you for the application note...

Winfred LU · ‎2021-08-29

The data inputs come in through the serial interface at each CLK rising edge and after 24 CLK cycles all data are loaded into the shift register.

Data latching can be done by setting the LE signal high during the last data loading CLK rising edge.

Then, when an enable signal (OER, OEB or OEG) is low, output terminals (R1-R8,G1-G8, B1-B8) respond to the data either ON or OFF.